436 MR. J. C. B. HENDY ON A " WASff-OrX " rOUJ!«D 



in most cases more numerous near the edges of the " Wash." 

 Several Stigmaria' have been found in the under-day. 



In every section examined, where there is evidence of lateral 

 pressure, the sides of the " Wash " are more or less " slickensided " ; 

 in other cases the sandstone of the " Wash " is found in immediate 

 contact with the coal, it being difficult sometimes to separate the 

 two, both being in a state of transition ; in other places the two 

 surfaces are dull and smooth, as in the ordinary bedding between 

 two strata. 



It is impossible to say hoAv far the " Wash " extends upwards ; 

 but, as the sandstone of the " Wash " is similar to that overlying 

 the shale, in all probability it does not reach beyond that bed. 

 Future workings in the Pleasley colliery will doubtless further 

 prove its course, but evidently it either disappears or takes a sharp 

 turn to the east, as shown by the present w^orkings in the Pleasley 

 pit. 



It has frequently been suggested that these "Wash-outs" are 

 due to " faulting" ; there is, however, little evidence of this here, 

 the only signs of " faulting " being the partly " slickensided " edges 

 and in some few places the dif^tortions of the coal next the " Wash " ; 

 these, however, are evidently due to lateral pressure and move- 

 ment, subsequent to the denudation of the coal and the deposition 

 of the " Wash " itself. Moreover it is difficult to conceive how any 

 " faulting," in the ordinary sense, could have taken place in the coal 

 or the measures above, without the sub-strata, or at any rate the 

 clay-floor, being at the same time to a certain extent dislocated or 

 disturbed; yet in all these sections the under-clay and the sand- 

 stone below are found in their normal condition, excepting as shown 

 in Section 4 (fig. 4), where the clay has been denuded at the same 

 time as the coal. 



The most striking peculiaiity of the " Wash-outs " found in this 

 district is doubtless the thickening of the coal at the edges. 

 Several " Washes " or " Drifts " have been found in the Durham 

 coal-field. The writer remembers examining a "Wash" at the 

 Middle Eeechburn colliery in the west of Durham, which was 

 first proved at the outcrop of the coal-seam, and followed by the 

 workings on each side for a distance of | of a mile into the hill- 

 side. The peculiar feature of this " Wash " was, that whereas that 

 near the outcrop consisted of sand and fine gravel, as the distance 

 from the outcrop and the depth of the superincumbent strata 

 increased, the sand gradually changed, first to a soft sandstone, and 

 ultimately, when a depth of 230 yards from the surface had been 

 reached, to a hard and compact sandstone, the change evidently 

 being due, to some extent, to the increased pressure, &c., of the over- 

 lying strata. In the Teversall " Wash-out," however, there is no 

 thickening of the coal, the measures having been simply denuded 

 and carried away in suspension by a pow^crful current. In the case 

 of the " Wash " at these pits from one third to one half of the coal 

 has been re-deposited in different places on the sides, the remainder 

 having evidently been carried away. It seems probable, therefore, 



